Tuesday, April 17, 2012

Stem cells

Stem cells

 In mammals, there are two broad types of stem cells:
  • embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and
  •  adult stem cells, which are found in various tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing adult tissues.
  • In a developing embryo, stem cells can differentiate into all the specialized cells (these are called pluripotent cells), but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.
There are three sources of autologous adult stem cells:


 1) Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest),

2) Adipose tissue (lipid cells), which requires extraction by liposuction, and

 3) Blood, which requires extraction through pheresis, wherein blood is drawn from the donor (similar to a blood donation), passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.

Stem cells can also be taken from umbilical cord blood.

Of all stem cell types, autologous harvesting involves the least risk. By definition, autologous cells are obtained from one's own body, just as one may bank his or her own blood for elective surgical procedures.

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